I don't recommend using the Bars Leak but if you're in a bind it is an interim fix.As I said later it probably needs the block or heads or both to be resurfaced to do the job properly.

I think I'll check out that stuff Pat mentioned by Subaru, sounds interesting in that it's a head gasket product.

Jaguar, and I'm sure some other manufacturers, actually advise using a 'sealing type' agent after major engine work, it's routine. What the heck, maybe I'll run some in my FE 'just because'!

Brent, are the head studs ARP? I think they have provisions in the ends for backing them out with a T-handle or allen wrench. So if you have to pull a head and worry about room, you can back the studs out and just pull the head right off.

PUll the studs and apply thread sealent. Pressure test the coolent system at 15 PSI for 24 hours. Allow for a 2 PSI drop for temp.

Just my thoughts.

:D

You are not the only with bad luck. I had 2 pond engines, problems with both. The first one had 2 sleeves that would not seat in the block, they sat about .15 too high on the deck, which would have warped the head or caused a leak!
My replacement block started to leak water out of the rear water jacket after about 2 hours of run time. Robert Pond took care of welding it, but I had a lot of work and expense due to this.
There are a lot of good suggestions on here already.
There should be a provision in the top of the studs for an allen wrench. If not, I would remove the studs using 2 nuts, tighten the top nut against the lower nut and then loosen the stud by turning the lower nut. They come out real easy, I know from experience!
If you want to try a sealant first, use Moroso Ceramic Seal, it has been widely used by racers for years in aluminum engines.
http://store.summitracing.com/partde...5&autoview=sku
The builder should have used arp sealant or equivalant on the threads, but they are human. That could be the culprit since you said it is the #8 cylinder and there is a water jacket back there. I do not know how the Shelby block is cast, I doubt the studs go into the water jacket, but that could be possible.
I build my own engines, it is not rocket science and is actually not very difficult.
I know most of the guys on here use builders and that works too, but when things like this happen, it puts you and the builder in an awkward position.
The problem could be his fault or it could be a bad casting or gasket.
I wish my 2 engines were the only bad luck I had!
I can make a pretty long list of broken components that I had to replace on my Kirkham build. If mine was done by a builder, he would have quit after this one!
Good luck!

I have to agree with fastrods, I used the Moroso product on my Mustang racer for some coolant leaks and it worked great. This may help eliminate the minor leak issue with coolant before going into a full teardown.

That Moroso Ceramic Seal is not compatible with antifreeze. That's a problem for many (most?) of the guys who drive on the street.

I had continuous head gasket problems with the motor I had,until I machined the block.No more problem.THere is another tread somewhere with a similar problem and it was found that the block had been machined ,but with a bad tool leaving deep machine grooves in the block.I have used Permatex Copper-spray a gasket with success in the past.

You have to find the problem before you start trying to fix it. Is the head gasket leaking, is the block leaking, does the head have a leak in one of the runners, has the sleeve dropped down and the head gasket not sealing and I have seen several intake gaskets leak into the end cylinders. I think they have added something to the anti-freeze in the last few years because we have seen some of it eat on the intake and head gaskets. You can do a leak down on the engine at the top and the bottom with the rockers of and you can pump up the radiator as mentioned before.
What block and heads are you using on your engine build? Good luck, Keith

Exactly. I had a problem with one of my engines leaking coolant into the oil, only under pressure. I took it to somebody who pressurized the system, then used a scope to look inside the engine to find the leak, and then fixed it appropriately. You can put a scope down an intake runner, or underneath the intake as indicated.